Highly Efficient Perovskite Blue Light-Emitting Diodes

Lead halide perovskite has attracted extensive attention during the past decade for applications in light-emitting diodes because of its wide emission tunability, high color purity, high quantum yield, and easy solution processibility. Despite the exciting progress of perovskite green, red, and near-infrared LEDs, fabrication of perovskite blue LEDs with high external quantum efficiency (EQE), high brightness, and high color purity remains a considerable challenge. Here, we report efficient perovskite blue LEDs with a world-record EQE of surpassing 22%, a peak luminance above 7000 cd/m², and a full width at half maximum of 15 nm. Besides, the devices exhibit a stable electroluminescence spectrum at constant elevated current injection. This performance is achieved by carefully manipulating the growth of perovskite into thin films with homogeneous isolated grains, which not only improve the light outcoupling efficiency but also enhance the spectrum stability.